A method of recycling and reconditioning a metal shipping container

ABSTRACT

A method of recycling a drum shaped metal shipping container which has at least two parts in overlapping relationship, the overlapping portions of said parts being secured together in liquid tight relation by an adhesive substance which when subjected to heat or an appropriate dissolving agent disintegrates so that said parts may be disassembled to make the container interior fully accessible for reconditioning. The adhesive substance is disintegrable and completely removable from the container parts without deforming the container parts or affecting the metallurgical properties of the parts.

United States Patent 51 3,660,188 Van Leer 451 M 2, 1972 [54] METHOD OFRECYCLING AND 2,936,261 5/1960 Cole ..156/283 x RECONDITIONING A METAL 5323 S l 1 SHIPPING CONTAINER 2,943,386 7/1960 [72] lnventor: Oscar J.Van Leer, North Holland, 3,454,179 7/1969 Netherlands FOREIGN PATENTS ORAPPLICATIONS [73] Assignee: Inland Steel Company, Chicago, Ill.

203,562 8/1955 Australia 156/322 1 Filed: l- 1969 884,225 l2/l961 GreatBritain... Appl' 869345 Primary Examiner-Benjamin A. Borchelt Related sApplication Data Assistant E.\'aminerDaniel Bent Att0rney-Wolfe,Hubbard, Voit, Leydig & Osann, Ltd. [63] Continuation-impart of Ser. No.648,647, June 26,

1967, abandoned. [57] ABSTRACT 52 U.S. c1 ..1s6 94,113 '12o A method ofrecyling adrum ap d metal shi in con- 5 1 1 1111.01 .3321) 35/00 minewhich has least Parts in relaimlshipv 58 Field 6: Search ..'.220/5, 5 A,67, 68, s1, so; 0"erlaPPing said lEms being sewed together 1 125/1201,120 BB 120 K, 120 M, 120 N 120 Y; in liquid tight relation by anadhesive substance which when l56/94 98 283 322 344 subjected to heat oran appropriate dissolving agent disintegrates so that said parts may bedisassembled to make the [56] Reterences Cited container interior fullyaccessible for reconditioning. The adhesive substance is disintegrableand completely removable UNITED STATES PATENTS from the container partswithout deforming the container parts or affecting the metallurgicalproperties, of the parts. 1,461,729 7/1923 Foster et a1. ..1 13/120 L UX2,424,188 7/1947 Pearson ..220/81 X 6 Claims, 9 Drawing Figures A METHODOF RECYCLING AND RECONDITIONING A METAL SHIPPING CONTAINER DESCRIPTIONOF THE INVENTION The present invention relates to recycling metalshipping containers and reconditioning such containers. This applicationis a continuation in part of the copending US. Pat. application of OscarJ. van Leer, Ser. No. 648,647, filed June 26, 1967, now abandoned.

Metal shipping containers are widely used for packaging, storage, andtransport of materials such as crude oil products, food products, liquidchemicals, paints and other liquid, semiliquid, pulverous or granularmaterials. In use, these containers may become damaged, dented orotherwise deformed. The contents also are frequently of the characterwhich, after emptying the container, leave a residue in the containerwhich cannot satisfactorily be removed when an attempt is made to usethe bung opening which provides an orifice of but limited size foraccess to and cleaning of the eontainers interior. A larger openingtherefore must be made which permits the insertion of suitable tools ordevices for the removal of dents and otherwise reshaping the walls ofthe container if necessary. To this end, it is known to cut the emptycontainer into two halves, clean and reshape the halves and again weldthe two parts together. This process, in addition to being a complicatedoperation, may considerably reduce the capacity of the container ifrepeated several times.

Accordingly, it is a general aim of the present invention to provide ashipping container the interior of which can easily and fully be madeaccessible for reconditioning and which after having been reconditionedcan be closed again to produce a complete containerwhich has the samecapacity and is indistinguishable from the original container.

It is an associated object to provide a shipping container ascharacterized above which may be simply and economically disassembledfor cleaning and reconditioning without damaging or deforming any partsof the container.

More particularly stated the present invention provides a container asset forth above which has essential parts intercom nected by an adhesivesubstance that is disintegrable and completely removable when subject topredetermined conditions so that the container parts may be disassembledfor cleaning and reconditioning, and then reunited by applying a freshadhesive substance to again produce a complete container having the samecapacity as originally.

Still another aspect of the invention is an improved method forproducing and reproducing a metal shipping container which is simple andeconomical and facilitates reconditioning of the container withoutdeforming any container parts.

Other objects and advantages of the invention will become apparent asthe following description proceeds, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a side elevation in partial section of a container madeaccording to the present invention;

FIG. 2 is an enlarged vertical section of the upper part of thecontainer shown in FIG. 1;

FIG. 3 is an enlarged vertical section of the lower part of thecontainer shown in FIG. 1;

FIG. 4 is an enlarged fragmentary section showing the connection of theend wall to the side wall of the parts shown in FIGS. 2 and 3;

FIG. 5 is an enlarged fragmentary section of the joint between the upperand lower parts of the container shown in FIG. 1;

FIGS. 6-8 show alternative forms of joint between the upper and lowerparts of the container; and

FIG. 9 is a fragmentary section of a modified form of end wallconstruction.

While the invention is susceptible of various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed, but, on the contrary, theintention is to cover all modifications, equivalents and alternativesfalling within the spirit and scope of the invention as expressed in theappended claims.

Referring now to the drawings, there is shown in FIG. 1 an exemplarydrum shaped shipping container 10 including a cylindrical side wallportion 11 enclosed by upper and lower end walls 12, 13 respectively.The walls of the container preferably are made from steel sheet metal,although it will be apparent that other materials could be used as well.The upper end wall 12 is provided with a filling and emptying opening 14and an air inlet and escape opening 15. To make the container liquidtight, the openings 14, 15 can be provided with appropriate removableclosures.

In order to permanently and reliably seal the end walls 12, 13 to theside wall 11 and at the same time enhance the rigidity of the structure,the end walls are cup shaped and a reinforcing ring 20 isprovided atboth ends of the container which surrounds the joint between the end andside walls. The cup shaped end walls each have a substantially flatbottom 21 and a skirt 22 interconnected by a curved portion 23. Theskirt 22 fits adjacent the side wall 11 and the parts may be securedtogether in any convenient manner, such as by welding. The reinforcingring 20 has a radial leg 25 mounted on the flat portion 21 of the endwall and axial leg26 engaging the inner side of the side wall 11 at itsextremity and is folded together with the side wall outwardly into abead 27.

In accordance with the invention, the container can be divided into atleast two parts so that the interior of the container is easily andfully accessible for reconditioning. After reconditioning the parts areadapted to be reunited to produce a complete container having the samecapacity and being indistinguishable from the original container. In theembodiment illustrated in FIGS. l-S, the container includes upper andlower parts 30 and 31, respectively, which mate in overlappingrelationship in the approximate circumferential plane of the cylindricalside wall 11. Each of the parts 30, 31 comprises one of the end wallsand a portion of the container side wall 11. To facilitate the handlingof the parts 30, 31 during manufacture and assembly, the height of eachpart may be made approximately half the height of the completecontainer.

In order that the upper and lower parts may be formed in overlappingrelationship, the upper part is fonned with a flaring extremity 32 whilethe lower part has a corresponding tapered extremity 33 of the sameinclination, which is shown as approximately 10:1. In order to cause atapered extremity 33 to be immediately adjacent the flaring extremity 32while the cylindrical side wall portion of each part has the samediameter, the tapered extremity 33 of the lower container part joins aflaring portion 34 which causes the'tapered extremity 33 to commence ata larger diameter. Thus, the lower part 31 has an extremity in the formof two truncated cones placed with their bases against each other. Tofacilitate manufacturing, the flaring portion 34 may have the sameinclination and width as the flaring extremity 32 and be spaced an equaldistance 'from its respective end wall so that the same die may be usedin manufacturing both parts 30 and 31.

In carrying out the'method of the invention and in order to secure theupper and lower container parts together, an adhesive substance isprovided between the overlapping portions of the side walls, saidadhesive being of a type which disintegrates when subjected topredetermined conditions so that the parts of the container may bereadily disassembled for reconditioning. As shown in FIG. 5, an adhesivesubstance 35 is provided between the tapered extremity 33 of the lowerpart and the overlapping flaring extremity 32 of the upper part. Theadhesive substance should be an appropriate material which will securelyhold together the container parts in liquid tight relation and willwithstand shock to and deformation of the walls during use of thecontainer. To permit disassembly and reconditioning of the container,however, the adhesive when subjected to predetermined conditions shouldbe disintegrable and completely removable from the container partswithout deforming the parts of afiecting the physical properties of theparts. Thus, the adhesive may be a substance which dissolves when asuitable solvent is applied, or which disintegrates when subjected toheat, either by melting or becoming brittle so that it falls into pieceswhen an external force is applied which is sufiicient to separate theparts of the container but insufficient to deform the parts. When a heatdestructible adhesive substance is used to secure metal container parts,the adhesive preferably should be disintegrable at temperatures which donot exceed 600 C. so that metallurgi: cal properties of the containerare not affected. To increase the strength of the joint in a metalcontainer, it may be desirable to apply an intermediate compound to themating surfaces in addition to the adhesive to compensate for anyoxidation preventing substances present at the metal interface.

According to the preferred embodiment of the invention,

the adhesive substance is a thermoplastic material such as a layer ofexpandable polyethylene. To promote oxidation and overcome the effect ofoxidation preventing substances between the polyethylene and matingmetal surfaces of the container, the surfaces may be coated with anintermediate layer of metal organic compound paint drier such as epoxyphenolic lacquer. The coated areas are then heated and a polyethylenepowder is applied to the hot areas. The excess of powder is shaken off,and the powdered sides are pressed against each other and simultaneouslyheated until the adhesive bond is completed between the parts. Such apolyethylene adhesive may be sufficiently cured at temperatures which donot exceed 200 C.

The use of expandable polyethylene as the adhesive provides theadvantage of filling any irregularities in the surfaces to be joined soas to achieve a liquid tight and uniform bond. The resulting bond alsohas a high stretchability and sheer resistance so that the joint willwithstand significant impact shocks and deformation during handling anduse of the container without affect the liquid tight seal. However, bymerely heating the polyethylene adhesive on the overlapping parts to atemperature in the range of 500 to 600 C., the adhesive will becomebrittleand disintegrate to permit easy disassembly of the containerparts. The adhesive may then be completely removed from the containerwalls without adversely affecting the walls.

Since the temperature required in curing the polyethylene adhesive tosecure the container parts is relatively low, an internal protectivecoating may be applied to the parts prior to their assembly. Mostprotective coatings, such as organic lacquers, are not affected by thepolyethylene curing temperature which preferably is below 200 C. Inaddition, since relatively low temperatures are involved in both curingand disintegrating of the adhesive, simple and economical heating meansmay be employed. Moreover, heating may be limited substantially totheadhesive and the overlapping portions of the container parts. Suchlocal heating has the advantage of permitting the remaining portions ofthe container to remain sufficiently cool to be handled manually. Thelower heat input also attributes to cheaper manufacturing andreconditioning operations and facilities.

It is understood that many low metal alloys, araldites, and metal gluesalternatively could be employed as effective adhesives. In each case,however, the adhesive should be of a type which permits application andremoval at temperatures of less than 600 C. Thus, welding and brazingtechniques would not be satisfactory. Such processes necessitatesignificantly higher temperatures which would destroy the necessarymetallurgical properties of the container in the joint area, as well asany protective coating applied to the interior of the container partsprior to assembly. The high welding and brazing temperatures also wouldtend to fuse or alloy the welded metal to the container walls, making itdifficult, if not impossible, to adequately remove the fused metalduring reconditioning without damaging the container.

It also should be appreciated that due to the tapered and flaredoverlapping extremities 32, 33 of the container shown in FIGS. 1-5, thecontainer parts are rigidly held together without slipping or shiftingduring the time the fresh adhesive is setting. Such stability ensuresthe creation of a good bond and also establishes an exact capacity ofthe container each time the parts are assembled.

In view of the above, it is apparent that the container made accordingto the present invention is a liquid tight and rigid unit of an exactcapacity. After the container has been used on one or more occasions itmay be readily divided into two parts by melting or otherwisedisintegrating the adhesive substance so that the interior of thecontainer is easily accessible for cleaning and reconditioning.Reconditioningmay include not only painting and reshaping of thecontainer, but also removing, replacing, or adding a desired lining orcoating to the container interior or exterior. After reconditioning, afresh adhesive substance can be applied and the parts united again toproduce a complete container which may have the same capacity and beindistinguishable from the original container. The separation of theparts by disintegrating the adhesive substance is a simple operationwhich does not destroy or deform any parts of the container and does notalter them in any irreversible way.

FIGS. 6-8 illustrate alternative ways in which the container may be madeup of overlapping parts secured by an adhesive substance according tothe present invention. The container of FIG. 6 is similar to the abovedescribed embodiment. The cylindrical container side wall includes onepart 50 formed with an outer tapered extremity 52 which is joined to thecylindrical portion of the side wall by a flared portion 53. The otherpart 51 of the side wall is formed with-a flared extremity 54overlapping the tapered extremity 52 and secured thereto by an adhesivesubstance 55. In this embodiment, the tapered extremity 52 is foldedback at its extreme edge to form a thick portion 56. The folded backedge 56 not only reinforces the edge but also seals the adhesive layer55 from the contents of the container,especially when the taperedextremity 52 extends beyond the placed sectum 54 into a cylindricalportion 57 of the container.

In the embodiments shown in FIGS. 7 and 8, the container side wall isformed with two identical halves in juxtaposed abutting relation and anannular part is provided adjacent the abutting extremities. In FIG. .7the container side wall has two halves 60, 61 each formed with flaringextremities 62, 63 interconnected by means of an inner double coned ring64 adhered to both extremities 62, 63 by an adhesive substance 65. FIG.8 shows a similar construction in which, however, the two identicalhalves 70, 71 of the container side wall have tapered extremities 72, 73joined with each other by means of an outer ring 74 and an adhesivesubstance 75. The use of identical container parts in the embodiments ofFIGS. 7 and 8 facilitates both manufacturing and reconditioning of theparts.

It is apparent that the container parts secured. by the adhesivesubstance may take still other forms. For example, the overlapping wallparts may be cylindrical with one part having an outer diameter which issmaller than the inner diameter of the other part such that an adhesivecan be present between the overlapping portion. Moreover, instead ofproviding the overlapping joint intermediate the ends of the side wall,alternatively the end'walls of the container could be secured to theside wall by means of such an adhesive substance. In each case, thecontainer parts to which the adhesive is applied should be inoverlapping relationship at approximately the circumferential plane ofthe side wall so that the container may be disassembled to provide fullaccess to the interior.

In addition, it will be apparent that the end walls of the container maytake other forms. However, to facilitate reconditioning and cleaning ofthe container after it is disassembled, the end walls preferably shouldhave as few crevices as possible. As shown in FIG. 9, a modified form ofend wall is welded to a container side wall 81 to form a crevice freeend closure that is especially suited for thorough cleaning. The endwall 80 in this case is of a one piece construction having a skirtportion 82 and a recessed central portion 84. The recessed centralportion 84 forms a reinforcing channel 85 and pennits an opening ring 86to be disposed below the end surface of the container. The skirt 82 issecured in abutting relation to the side wall 81 by an appropriateweldment so that there are no crevices created by the joint between thetwo members. Again, as in the previous embodiment, the end wall 80 ispermanently secured to the side wall 81, while the side wall may beseparable to permit reconditioning of the container.

In view of the above, it can be seen that the container of the presentinvention is produced and reproduced by an improved novel method whichis simple and economical and facilitates reconditioning of the containerparts It has been shown that the container is produced by forming partswhich when assembled are in partially overlapping relation, assemblingthe parts together, and securing the overlapping portions of the partsto one another in liquid tight and rigid relationship by means of anadhesive substance that is disintegrable when subjected to predeterminedconditions to permit separation of the parts without deforming ordamaging the parts.

I claim as my invention:

1. A method of reconditioning a reusable metal shipping container of thetype which has at least two parts in overlapping relationship, theoverlapping portions of said parts being secured together in liquidtight relation by a thermoplastic adhesive substance which remainsdistinct from the metal of container parts and which is disintegratablewhen subject to predetermined conditions comprising the steps ofdisintegrating said adhesive substance while maintaining said containerparts in the same physical shape and with the same metallic strength andflexibility as when said parts were secured by said adhesive, separatingsaid container parts to make accessible the interior of said containerparts, removing completely the disintegrated adhesive from said parts,reconditioning and cleaning said container parts, applying a freshcoating of said adhesive substance to the portions of said containerparts which overlap when said container is in an assembled condition,and reuniting said container parts to produce a complete containerhaving the same capacity as originally.

2. The method of claim 1 in which said adhesive is disintegrated byheating said adhesive to a temperature below that which affects themetallic strength and flexibility of said adjacent container parts.

3. The method of claim 2 in which said adhesive is disintegrated byheating it to a temperature not in excess of 600 C.

4. The method of claim 2 in which heating to disintegrate said adhesiveis limited substantially to the overlapping portions of said parts andsaid adhesive.

5. The method of claim 1 including applying a protective coatingsubstance to the interior of said container parts after cleaning of saidparts and prior to applying a fresh adhesive coating, and applying saidadhesive and reuniting said parts without destroying said protectivecoating substance.

6. The method of claim 2 in which an expandable polyethylene adhesive isapplied to said overlapping container portions.

2. The method of claim 1 in which said adhesive is disintegrated byheating said adhesive to a temperature below that which affects themetallic strength and flexibility of said adjacent container parts. 3.The method of claim 2 in which said adhesive is disintegrated by heatingit to a temperature not in excess of 600* C.
 4. The method of claim 2 inwhich heating to disintegrate said adhesive is limited substantially tothe overlapping portions of said parts and said adhesive.
 5. The methodof claim 1 including applying a protective coating substance to theinterior of said container parts after cleaning of said parts and priorto applying a fresh adhesive coating, and applying said adhesive andreuniting said parts without destroying said protective coatingsubstance.
 6. The method of claim 2 in which an expandable polyethyleneadhesive is applied to said overlapping container portions.